The present invention relates to a device for examining the anterior and the posterior segments of a patient's eye, the device having a stereoscopic microscope system and an oscillating slit illuminator disposed in viewing direction downstream of the stereoscopic microscope in longitudinal direction to two parallel optical beam paths, so-called stereoscopic beam paths, passing through the stereoscopic microscope, in longitudinal direction to whose stereoscopic beam paths, are provided a binocular optic having a downstream binocular tube objective system, an interchangeable Galilean optic and a main objective.